Author(s): W. Baumann; L. Carteciano; D. Weinberg

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Abstract: The IAHR Working Group on Advanced Nuclear Reactors Thermal Hydraulics has carried out a Benchmark exercise on thermal propagation effects in a vertical turbulent flow behind a jet block, with water and sodium as the working fluid. The jet block initiates a multi-jet flow, where all jets have the same velocity, and the central jet is heated. The main interest aims at the developing temperature field downstream. A total of 8 computational methods were applied to the Benchmark problem. They cover the adaptation of mesh grid and boundary conditions, the use of various differencing schemes for reducing numerical diffusion, adjustment of the turbulent Prandtl number, and the investigation of buoyancy effects within the turbulence model equations. Most of the predictions achieved by the applied computational methods come close to the experimental data when the turbulent Prandtl number is adjusted to give agreement with control results which were part of the issued Benchmark problem description. As one of the important findings, however, it turned out that this tuning of the turbulent Prandtl number can be dispensed with by upgrading the computational methods with the transport equations of turbulent heat flux.

DOI: https://doi.org/10.1080/00221689709498393

Year: 1997